Jake Gyllenhaal says his sex scenes with Anne Hathaway in new film Love And Other Drugs are musical.

In the movie based on James Reidy's best-selling autobiography, Hard Sell: The Evolution Of A Viagra Salesman, the Hollywood heartthrob plays a Viagra salesman who falls for a woman with early-stage Parkinson's, and is determined to bed her on the first date.

Jake told Esquire: "There's something about the way Annie and I both work which is inherently very musical. It's all about rhythm. There's a rhythm to writing, there's a rhythm to sports, there's a rhythm to sex."

The Donnie Darko star admitted filming sex scenes were always awkward, even though he and Anne had done one before for Brokeback Mountain.

He said: "Annie and I had already had sex on film. Look, it is uncomfortable - no matter what. There are people around, and the thing about any intimate relationship is that usually, in the majority of cases, there isn't a film crew involved."

But Jake claims he felt comfortable stripping for the camera, although director Ed Zwick was worried about his muscly physique after filming action movie Prince Of Persia.

Jake said: "Ed was a little worried about it. He was like, 'You're not going to be all buff are you?' It felt good just to be myself, naked."

And while Jake was comfortable in the nude, surrounded by all the film crew, he was still surprised Anne was too.

He said: "Eventually there was a real intimacy among the crew, a real respect, particularly for Annie, because as a woman I think it's harder. She said at one point, 'Well, we're both topless and we both show our butts.' And I was like, 'Hmm, but it's a little different for you.'"

:: The full interview is available in the December issue of Esquire, on sale on Thursday.